Air carts for use on agricultural implements are well known. Typically, these air carts are used as part of an air seeder in which seeds, fertilizer and herbicides are deposited onto and into the ground during the planting operation. Air seeders and other seeding devices are commonly towed by tractors to apply seed or fertilizer, or both simultaneously, to a field. For example, an air seeder may be towed in combination with a tilling implement, one behind the other, to place the seed and fertilizer under the surface of the soil. Generally, air carts are in either a two container or three container configuration. The two container configuration is used to carry a supply of seeds and fertilizer for planting into the ground. The three container configuration can be used to carry an additional element, such as an herbicide, to be deposited on the ground. The three container configuration, however, can also be used to carry only one or two materials in whatever amounts are desired.
Air seeders also typically include a metering system for dispensing product from the tanks and a pneumatic distribution system for delivering the product from the tank to the soil. The tanks of the air seeders are formed with bottom surfaces that slope downward at the angle of repose for the product toward the metering mechanism. Gravity, in combination with the vibrations and movement of the air seeder, act to move the grain from the perimeter of the tank toward the metering mechanism located at the center of the tank.
Such movement of the product can be inefficient, and seed and/or fertilizer is often left behind when the volume in the tank becomes low. While this small amount of seed/or fertilizer does not substantially interfere with the ongoing operations of the air seeder, the seed or fertilizer that is left in the grain tank over extended periods of time, such as during storage of the air seeder between seasons, will likely spoil. This spoiled product will then be discharged from the air seeder the next time it is used, leading to contamination of the newly added product. Moreover, the spoiling or rotting process of the seed or fertilizer in the air seeder tank can be corrosive to the air seeder. Over time, the air seeder tank can be damaged and require repair. Additionally, any product that is left in the tank when the tank is switched to a different product will exit the air seeder with that new product. For example, if the tank has been used to dispense fertilizer, fertilizer will remain in the tank and will be intermingled with, for example, seeds when the tank is next used. This could be damaging to the seeds. Moreover, operators of air seeders demand that almost all product drain evenly from the tank with each use so that greater field efficiency can be achieved.
Further, it is desirable to increase the volume of the air seeder hopper so that more ground can be covered without having to stop and re-fill the tanks. However, if larger tanks are employed, the air seeder becomes unstable due to an excessive center of gravity. Additionally, in a large capacity two tank system, the optimal design would typically place the rear metering mechanism rearward over the axle. However, this causes interference both with clean out and with the location of the metering mechanism in a gravity fed tank. In order to translate the slopes and drain the tanks to one metering location, the tanks must be moved forward, thereby increasing the frame length and making the tanks even more unstable.
Accordingly, it would be desirable to provide a large capacity air seeder hopper which can carry a large volume of product and efficiently transport the product to the metering mechanism and overcome the aforementioned disadvantages of the current state of the art.